So, he's opted to remove the ability for employees to have a time delay for communication. I don't know about anyone else, but if my life is full of IMs, phone calls, and drive-by conversations and I can't get a blinking thing done. If it's not urgent, send an email ...and most issues at my workplace really do fall into the "not urgent" category. It would be utterly inefficient to interrupt my workflow every 15 minutes for an instant conversation.
Email also has the benefit of making the writer organize his/her ideas better. Plus, commitments are in writing. It's less likely for an email to be misinterpreted, but conversations can always be remembered in "creative" ways. The only people I've ever met who refused to do email were people who didn't want to be pinned down.....wanted to leave their options open, usually to stick other people with the work to do and/or the blame for a mistake.